DES加密算法的C语言实现，包括测试及演示，包你所求-DES encryption algorithm in C language implementation, including the testing and demonstration, packet you seek

编程实现S-DES算法的加密与解密过程，采用加法链求大数的指数及模-RSA-Programming Algorithm S-DES encryption and decryption process, using Addition Chains seek large numbers of the index and model-RSA